THIS is how wars usually start: with a steadily escalating stand-off over something intrinsically worthless. So don't be too surprised if the US and Japan go to war with China next year over the uninhabited rocks that Japan calls the Senkakus and China calls the Diaoyu islands. And don't assume the war would be contained and short.

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It seems almost laughably unthinkable that the world's three richest countries - two of them nuclear-armed - would go to war over something so trivial. But that is to confuse what starts a war with what causes it.

The conflict is really about China challenging the US in the Pacific, White says. President Obama has vowed a Pentagon "pivot to Asia," itself a response to China's growing strength.

Claiming the Senkaku islands, a series of small outcroppings in the East China Sea, is China's way of testing America's new posture, White says.

And it's this kind of tit-for-tat that inevitably causes someone to open fire.

The risk is that, without a clear circuit-breaker, the escalation will continue until at some point shots are exchanged, and a spiral to war begins that no one can stop. Neither side could win such a war, and it would be devastating not just for them but for the rest of us.